The 5′ RACE analysis of the CD5 gene initiation and expression in B and T cells. (A) CD5 5′ RACE analysis of exon 1 B (E1B). One band from T lymphocytes (899 bp) and 2 from tonsillar B cells (1096 bp, 899 bp) were separated, subcloned into pTrueBlue, and sequenced. The larger band amplified only from B-cell RNA contained E1B instead of E1A. (B) Regulatory motifs for transcription factor binding and TATA box location within the U3 region. Box delimits the U3/R/U5 parts. The 5′ RACE sequences are underlined. (C) RT-PCR analysis of cDNA from B or T cells using sense primers specific for CD5 exon 2, E1A, E1B, and antisense primers located at the exons 5-6 junction. Daudi B cells and Jurkat T cells are negative and positive controls.